The overall objectives of this study are to investigate the nature of the link between insulin binding and insulin action in isolated rat hepatocytes, and to elucidate the mechanism of insulin resistance at the receptor-effector interface. A three-pronged attack is outlined to examine the problem. The first step is to investigate a temperature dependent decrease in number of binding sites at 37 degrees centigrade relative to 20 degrees centigrade. This is important because of the necessity of evaluating binding at physiological temperatures in order to compare it with action. The temperature dependence of the binding will be investigated systemically between 5 degrees centigrade and 37 degrees centigrade. Second, the nature of negative cooperativity in hepatocytes will be investigated. New types of experiments to assess the extent of receptor occupancy during the dissociation phase of a DeMeyts' type negative copperativity experiment will be discussed. In addition the effect of anti-insulin antibody in insulin binding, negative cooperativity, and insulin action will be examined. Third, the correlation of insulin binding and insulin action in several pathophysiologic states will be studied. A method for measuring insulin action on hepatocytes involving net incorporation of C to the 14th power glucose into glycogen is outlined. Binding and action will be correlated in control, fasted, streptozotocin diabetic, treated diabetic, aged-obese, and infected rats.